Mineral fibre products generally comprise man-made vitreous fibres (MMVF) such as, e.g. glass fibres, basalt fibres, slag wool, mineral wool and stone wool, which are bonded together by a cured thermoset polymeric binder material. For use as thermal or acoustical insulation products, bonded mineral fibre mats are generally produced by converting a melt made of suitable raw materials to fibres in conventional manner, for instance by a spinning cup process or by a cascade rotor process. The fibres are blown into a forming chamber and, while airborne and while still hot, are sprayed with a binder solution and randomly deposited as a mat or web onto a travelling conveyor. The fibre mat is then transferred to a curing oven where heated air is blown through the mat to cure the binder and rigidly bond the mineral fibres together.
One problem frequently encountered in the production of such mineral fibre products is an insufficient curing of the binder. Insufficient curing can for example occur in case there is an inhomogeneous binder distribution resulting in a high local concentration of binder which cannot be cured during the passage in the curing oven (5-10 minutes).
This phenomenon is termed “wet spots”. Wet spots may result in poor performance of the installed product. The wet spot may diffuse into other surrounding building material, for example the mortar of external insulation and an unaesthetical spot may be seen on the outer wall because of the wet spot.
Insufficient curing may also occur throughout the whole product. This may be the case where the production line has a production change from one product type to another and where the curing settings needs to be changed. For example, changing from a low binder content product to a high binder content product, or vice versa. During the run-in of the line, the curing settings may not be optimal and insufficient curing occurs.
Another problem that can occur during the production of mineral fibre products are anomalies of the binder distribution like the agglomeration of large amounts of binder in a single part of the mineral fibre product (called “chewing gums”).
Accordingly, there is a need for a method that allows the rapid detection of curing and/or the local distribution of curing of the binder material, and/or of anomalies of the cured binder in a mineral fibre product. Previously known methods for the detection involve the thorough inspection of the mineral fibre products in combination with reagents which chemically react with one or more of the components of the binder in order to allow a detection. These methods involve harmful chemicals and are therefore not convenient for a quick and efficient quality control of mineral fibre products.
In view of the foregoing, it would be a significant advancement in the art to provide a method for detecting curing and/or of the local distribution of curing of the binder material, and/or of anomalies of the cured binder, on a mineral fibre product that allows a rapid and secure detection. It would be a further advancement in the art if such a method could be performed without the use of harmful chemicals and without destroying the tested mineral fibre product.